The research program involves study of the genetics and genetic biochemistry of selected strains of mammalian cells in vitro before and after treatment with mutagenic agents and agents which cause irreversible malignant transformation and reversible conversion between epithelial-like and fibroblast-like states which resemble those of malignantly transformed and normal cells respectively. A variety of specially prepared hybrid cells with genetic constitutions designed to affect these properties will also be studied. These cells will also be examine for tumor production in the Syrian hamster cheek pouch. Attempt will be made to analyze, as carefully as possible, single gene mutation and chromosomal variations and their biochemical concomitants which affect transformed properties in vitro and malignancy in vivo. BIBLIOGRAPHIC REFERENCE: Puck, Theodore T. Somatic Cell Genetics in Problems Related to Differentiation, in (Monograph) Advances in Pathobiology, ed. C. M. Fenoglio and D.W. King, Stratton Intercontinental Book Corp., New York, in press (1976).